/*
 * Copyright (C) 2019 by Sukchan Lee <acetcom@gmail.com>
 *
 * This file is part of Open5GS.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#if !defined(OGS_GTP_INSIDE) && !defined(OGS_GTP_COMPILATION)
#error "This header cannot be included directly."
#endif

#ifndef OGS_GTP_XACT_H
#define OGS_GTP_XACT_H

#ifdef __cplusplus
extern "C" {
#endif

/* 
 * p225-226 Chapter 7.6 in TS 29.274 V15.9.0
 * 
 * A Sequence Number used for a Command message shall have the most significant
 * bit set to 1. A Sequence Number in a message, which was triggered by
 * a Command message, as well as respective Triggered Reply message
 * shall have the same Sequence Number as the Command message
 * (i.e. shall also have the most significant bit set to 1).
 *
 * This setting of the most significant bit of the Sequence Number is done
 * to avoid potential clashes between the Sequence Number selected for
 * a Command message, and the Sequence Number selected by a GTPv2 peer
 * for a Request message, which was not triggered by a Command message.
 *
 * A Sequence Number used for a Request message, which was not triggered
 * by a Command message shall have the most significant bit set to 0.
 */
#define OGS_GTP_MIN_XACT_ID             1
#define OGS_GTP_CMD_XACT_ID             0x800000

/**
 * Transaction context
 */
typedef struct ogs_gtp_xact_s {
    ogs_lnode_t     node;           /**< A node of list */
    ogs_index_t     index;
    
#define OGS_GTP_LOCAL_ORIGINATOR  0
#define OGS_GTP_REMOTE_ORIGINATOR 1
    uint8_t         org;            /**< Transaction' originator. 
                                         local or remote */

    uint32_t        xid;            /**< Transaction ID */
    ogs_gtp_node_t  *gnode;         /**< Relevant GTP node context */

    void (*cb)(ogs_gtp_xact_t *, void *); /**< Local timer expiration handler */
    void            *data;          /**< Transaction Data */

    int             step;           /**< Current step in the sequence.
                                         1 : Initial 
                                         2 : Triggered 
                                         3 : Triggered-Reply */
    struct {
        uint8_t     type;           /**< Message type history */
        ogs_pkbuf_t *pkbuf;         /**< Packet history */
    } seq[3];                       /**< history for the each step */

    ogs_timer_t     *tm_response;   /**< Timer waiting for next message */
    uint8_t         response_rcount;
    ogs_timer_t     *tm_holding;    /**< Timer waiting for holding message */
    uint8_t         holding_rcount;

    void            *assoc_xact;    /**< Associated GTP transaction */
    void            *pfcp_xact;     /**< Associated PFCP transaction */

#define OGS_GTP_MODIFY_TFT_UPDATE ((uint64_t)1<<0)
#define OGS_GTP_MODIFY_QOS_UPDATE ((uint64_t)1<<1)
    uint64_t        update_flags;

#define OGS_GTP_DELETE_SEND_AUTHENTICATION_REQUEST 1
#define OGS_GTP_DELETE_SEND_DETACH_ACCEPT 2
#define OGS_GTP_DELETE_SEND_DEACTIVATE_BEARER_CONTEXT_REQUEST 3
#define OGS_GTP_DELETE_SEND_UE_CONTEXT_RELEASE_COMMAND 4
#define OGS_GTP_DELETE_HANDLE_PDN_CONNECTIVITY_REQUEST 5
    int             delete_action;

#define OGS_GTP_RELEASE_SEND_UE_CONTEXT_RELEASE_COMMAND 1
#define OGS_GTP_RELEASE_S1_CONTEXT_REMOVE 2
    int             release_action;
} ogs_gtp_xact_t;

int ogs_gtp_xact_init(void);
void ogs_gtp_xact_final(void);

ogs_gtp_xact_t *ogs_gtp_xact_local_create(ogs_gtp_node_t *gnode,
        ogs_gtp_header_t *hdesc, ogs_pkbuf_t *pkbuf,
        void (*cb)(ogs_gtp_xact_t *xact, void *data), void *data);
ogs_gtp_xact_t *ogs_gtp_xact_remote_create(
        ogs_gtp_node_t *gnode, uint32_t sqn);
ogs_gtp_xact_t *ogs_gtp_xact_cycle(ogs_gtp_xact_t *xact);
void ogs_gtp_xact_delete_all(ogs_gtp_node_t *gnode);

int ogs_gtp_xact_update_tx(ogs_gtp_xact_t *xact,
        ogs_gtp_header_t *hdesc, ogs_pkbuf_t *pkbuf);
int ogs_gtp_xact_update_rx(ogs_gtp_xact_t *xact, uint8_t type);

int ogs_gtp_xact_commit(ogs_gtp_xact_t *xact);

int ogs_gtp_xact_receive(ogs_gtp_node_t *gnode,
        ogs_gtp_header_t *h, ogs_gtp_xact_t **xact);

ogs_gtp_xact_t *ogs_gtp_xact_find(ogs_index_t index);
ogs_gtp_xact_t *ogs_gtp_xact_find_by_xid(
        ogs_gtp_node_t *gnode, uint8_t type, uint32_t xid);
void ogs_gtp_xact_associate(ogs_gtp_xact_t *xact1, ogs_gtp_xact_t *xact2);
void ogs_gtp_xact_deassociate(ogs_gtp_xact_t *xact1, ogs_gtp_xact_t *xact2);

#ifdef __cplusplus
}
#endif

#endif /* OGS_GTP_XACT_H */
